"Unbreakable skin" refers to having skin that is extremely strong and cannot be easily damaged or harmed.
Sentences with «unbreakable skin»
Oh, and while the bartender was not actually Luke Cage... he did manage to make me the best Bloody Mary I have ever had, so I'll forgive him for not being a superhero with unbreakable skin. (have-clothes-will-travel.com)
The first season of «Luke Cage» brought to Netflix Mike Colter as the titular hero, who gains super strength and unbreakable skin after a sabotaged. (awfj.org)
In case you hadn't noticed, he's super big and super strong, with unbreakable skin and an massive axe which would make Thor weep. (gamesradar.com)